These studies were undertaken to develop methodology for immunoassay of environmental chemicals. Current interest centers around chemicals which are lipid soluble in contrast to those which are water soluble. Chemicals currently under investigation are 2,3,7,8-tetrachlorodibenzo-p-dioxin and a model chlorinated biphenyl. Areas of present interest include (1) methods for coupling of haptenic environmental chemicals to carrier molecules to be used as antigens; (2) effects of halogens on immune response; and (3) methods for immunoassay of environmental chemicals.